Electromagnetic actuator for contactors and circuit breakers



A ril 8, 1952 A. BLANCHET 2,591,773

ELECTROMAGNETIC ACTUATOR FOR CONTACTORS AND CIRCUIT BREAKERS Filed March 3, 1949 2 SHEETS-SHEET 1 April 8, 195? A. BLANCHET 2,591,773

ELECTROMAGNETIC ACTUATOR FOR CONTACTORS AND CIRCUIT BREAKERS Filed March 3, 1949 2 SHEETS-SHEET 2 Fig. 2. 33 1 2 24 mum Patented Apr. 8, 1952 ELECTROMAGNETIC ACTUATOR FOR CON- TACTOHS AND CIRCUIT BREAKERS Andr Blanchet, Neuilly-sur-Seine, France, as-

signor to Societe trique, N anterre,

Application In France 3 Claims. (Cl. 1 75-'-345) This invention relates to an electromagnetic actuator for contactors and circuit-breakers and has reference to devices of the type having a pivotally mounted armature, particularly those in which the opening and closing of contacts is effected by means of a pivoted plate or pallet carrying an armature which is subjected to the field of an electromagnet. Up to the present time arrangements of this kind have only attained a sufficient degree of refinement-notably as regards silence in operation, reduction of residual magnetism, and reliability under intensive working conditions-at the cost of certain complications in their construction.

The present invention aims to provide a new mode of construction for such electromagnetic actuators, the apparatus being characterised by some or all of the following features taken separately or in combination:

(a) Actuation of the armature-carrying pallet by the movable armature is effected at a point or points which is or are farther from the pivotal axis of the said pallet than that limb of the electromagnet which is itself farthest from this same axis.

The operative connection may be effected by simple abutment of one surface of the movable armature against a corresponding surface of the pallet. I (b) The movable arm ture is mounted on the supporting pallet free from all elastic, pivoted or fixed attachment and is held in all directions with a slight amount of clearance. In particular. this hold may be effected:

On its rear face, by the supporting pallet.

On its sides, by lateral zones of the said pallet which has a section in the shape of a U.

Towards the front, by a recurvature, at about 180, of the upper end of the supporting pallet, or by an added member of similar shape, forming a stop both upwards and towards the front, and, on the other hand, by a lower stop associated with the pivot on which the pallet is mounted, this stop forming, when at rest, a lower fulcrum of the movable armature and limiting towards the front the movements of its lower part.

This construction does away with all shafts, springs, guiding members or like parts of a dellcate and costly construction. It allows the movable armature to be constructed by the simple riveting together of laminae while the supporting pallet can be formed by cutting and shaping of sheet metal, instead of using cast or moulded parts such as are generally employed. It ensures for the movable armature a greater latitude in its La Telemecanique France, a French society March 3, 1949, Serial No. 19,335

Elec- April 22, 1948 2 movements and, consequently, gives better contacts with the fixed armature, while yet limiting, in a predetermined manner, the possible-movements of the armature. It ensures for the free armature an attraction couple on the highest-axis of the pallet, owing to the fact that the attraction is exerted on the upper part of the pallet, that is to say, the part most distant from the axis of.

rotation.

It improves the silence of working, owing to the fact that the actuation of the pallet at a point further from the pivotal axis than the polar faces, has the effect of producing a tendency for the movable armature to rock about the upper polar face of the magnet core when it is in the contact position, thereby augmenting the-force of application of the lower polar face of the movable armature to the corresponding face of the magnet core. e

(0) The magnet core comprises three limbs which, according to the present invention, may be constructed as follows:

Oil the limb farthestfrom the pivotal axis of the pallet is mounted a dephaslng coil. j v

On the central hub is mounted the exciting coil and the latter'is arranged in such a way as to leave a small air gap between its own polar face and the corresponding face on the movable armature. This exciting coil may be constituted by two juxtaposed windings. These two windings can be separated by apartition provided with eyelets carrying terminals which also serve as a means for fixing the coil to the electromagnet with the aid of sleeves connected to the frame of the apparatus. v

The limb nearest to let comprises a zone of reduced cross-section being that of the master plates only.

These devices have the following advantages:

l-Avoidance of sticking of the moving armature due to the effect of residual magnetism-because the air gap prevents the formation of a perfect magnetic circuit between the central pole of the magnet core and one or other of the outer poles thereof.

The region of reduced cross-section in the lower limb of the magnet core produces a higher degree of magnetic saturation in this region and also prevents the formation of a perfect magnetic circuit between the outside metal cheek plates.

2--Reduction in the weight of the magnet core.

3-The attainment of perfectly silent working with only a single dephasing coil. Oscillation about a point or central axis is rendered impossible by the presence of the small central air gap the pivotal axis of the pal-.

3 and from this it follows that the freely movable armature is maintained in its position of contact solely by pressure acting at its extreme poles; moreover, the lower pole face of the said armature is held not only by the attraction of the lower limb of the. magnet core but also by the effect of a rocking tendency due conjointly to the attraction of the middle and upper limbs of the magnet and to a reverse pull exerted at the uppermost part of the free armature, by an abutment of the relatively movable pallet.-

The various characteristics of the apparatus according to the invention and the. advantages;

which they afford will be further elucidated in the course of the following description, with reference to the accompanying drawings. of. one.

practical embodiment which is to be regarded merely as an example. In the said drawings:

Figure 1 is a side view partly in section of the improved electromagnetic actuator, the free armature being in. the. closed position (ie-. held magnetically in contact with. the magnet) Figure- 2 is a similar view: withthefree armature in open position (ie;. released fromthe magnet);

Figure'3isa rear view of the. device in section on the plane CD in Figure 1.

Figure 4 is a view' showing the free armature in section on the plane AB of Figure 1.

Like reference numerals. designate like parts in all figures.

Accordingto this constructional examplethe fixed" magnet core is built up: on central master plates I and 2, on to which are. fixed, by rivets 3- and 4, metal laminae 51 which are held. together n byl'ateral master plates or check plates 8 and i.

As; shown in Figuresl and 2', this. core has three-limbs 8, 9, and Ill. The limb 8,. whichlies farthest from the axis H about whichthe pallet IZI-pi-vot's, carries'a dephasing coil. [3; thecentral limb" 9-; surrounded'by the energisingi winding 3 3, is arranged so as to leave an airgap is between its: polar face s and the movable armature. l While the lower limb lllthatis to say, the one nearest to the pivotal axis l'l: includes aregion l6 wherein the cross-section is. reduced: to that ofithe mast'er plates I 2, 6 and 1 (see Figure 3).

The movable armature I5 is somounted. on the pivoted supporting pallet I2 sov to have acertain amount of free movement relatively to said pallet; Said armature is built up of metal laminae H heldtogether by lateral cheek plates l3 and rivets Ill. The positioningof said: free. armature inrelation to the pivoted pallet is eifected:

At its rear face (i. e. the face most remote from the fixed magnet core) by inwardly directed projections 20, 2|, on the pallet I2.

At its sides by lateral flanges 22 and 23 on the pallet l 2.

Adjacent its top end and frontally by a recurvature- 24 of the pallet l2 producing a downturned lip or flange (as seen in Figures 1 and 2).

Adjacent its bottom end and frontally' by a supporting retaining member or stop 25; secured to the pallet l2 by a screw 26 and pivoted at H on a'bracket'member 21, fixed at 28 to the master plates I and 2.

The armature-retracting system comprises a tension spring 29 the tension of which can be regulated by means ofa screw and lock-nut assembly 30 and which acts upon a prolongation 31; ofthepallet l2.

An abutment member 32, secured to the fixed magnet core at 33, co-acts with the upper part ofthe pallet l2 to limit outward movement of T said pallet and of the free armature carried thereby.

The winding 35 which surrounds the middle limb 9 of the magnet core, is divided into two separate coils by a partition 35 on which are mounted, on opposite sides'of the apparatus, terminals 36, serving" with the aid of sleeves 31. for mounting the winding on the support which car'- ries the magnet core. Bolts 38, insulated electrically from the member I, may, if desired, serve as terminalsif the sleeves 3'! comprise internal conductors this arrangement permits of all the electric connections being located on the rear face 3! of the apparatus.

The various parts are dimensioned in such a way that in. the closed position of the actuator. (i. e. when the free armature is attracted) the said free armature bears only against the downturned lip produced by the recurvature 24 of the pallet and against the limbs 8 and II] of the magnet core.. In other. Words said. armature stands clear of the supporting: projections ZDJand 2| of the-palletand clear of the-vertical. face: of the stop 25.

Theprincipal advantages of this apparatus are the following:

(a) Extreme simplicity of construction. The

pallet I2, for instance, can be stamped from sheet metal and pressed to shape. Flexible fixing bolts, springs, spindles and collars as usedheretofore for mounting movable armatures in-devices of the type referred to, are eliminated. Dismantling can be effected immediately, since by undoing the screw 26, it ismadepossible to. release the free. armature completely.

(b) The fact that the movable armatureis free within.suitablypredetermined limits to move in all directions facilitates. the. preparation. or truing of. the. polefaces. which. thereafter, without further difficulty, contact. each. other per.- fectly.. Thesame. arrangement also contributes to. the avoidance of. oscillation or chattering. of the. movable armature and so ensures silent working 7 (c). 'Ifhepallet l2, acting, on the upper. end 40 either freely movable armature, under the-influence of the spring 29 (Figure. l) as well. as under any other retractive influence, produces. a rocking efiect which tends to apply the lower polar; face 4'! firmly against'thelimb ill of the magnet core since the free armature does not even in the closed position abut against the stop 25. The reduction in cross-sectional area of the limb it at the region I6 is so proportioned that the pressure at 4| resulting from the magnetic attraction combined with the aforesaid rocking effect shall be approximately equal to the pressure with which the polar face 42 is applied to. the upper magnet limb 8.

(d) The air gap provided at [4 avoids all possibility of the movable armature oscillating about its centre, it also prevents the formation between the central limb 9 and one o the other ofthe outer limbs 8. and Ill, of a perfect (all-iron) mag netic circuit, which could give rise to sticking; of the armature as the result of a state of permanent magnetism. The presence of the air gap l4, therefore, facilitates a quick release of the armature.

(e) The described arrangementsmake it possiblewith the useof only a single dephasingcoil to obtain perfectly silent working, because all risk of oscillation of the movable armature is suppressed and because the lower polar face of the said armature is pressed against the fixed magnet core by the rocking action explained.

(I) The terminals serve for fixing the coil.

It is quite evident that within the scope of the invention various modifications may be made in the device as herein described and shown in the accompanying drawings. In particular, certain features may be omitted, although the whole device as herein disclosed constitutes a preferred constructional form of the invention.

Thus for example, instead of the pallet being driven at a point remote from its pivotal axis by simple abutment means, it may be driven by an articulating shaft or spindle: also, instead of the movable armature being positioned by lateral checks on the pallet, it may be guided by one or more grooves or ridges formed in the body of the armature itself or by additional o connected pieces. In like manner the invention may be applied to electromagnets with any number of polar limbs other than three.

I claim:

1. An electromagnetic actuator for contactors and circuit breakers, comprising in combination, a frame; an E-shaped magnetic core arranged on said frame having a first and a second outer and an intermediate central limb, only said second outer limb having a zone of reduced crosssection so that said first oute limb has a greater force of attraction than said second outer limb when said core is energized; a pin arranged on said frame near said second outer limb; a pallet pivotally mounted on said frame for rocking motion about said pin; resilient means operatively connected to said pallet to urge the same into an end position farthest away from said core; a laminated armature cooperating with said magnetic core; and holding means on said pallet cooperating with said armature to hold the same with play allowing a limited displacement of said armature with respect to said pallet in all directions, said holding means including a holding member limiting movement of said laminated armature in a direction away from said pallet and located at a greater distance from said pin than said first outer limb of said core.

' 2. An electromagnetic actuator for contactors and circuit breakers, comprising in combination, a frame; an E-shaped magnetic core arranged on said frame and having a first and a second outer and an intermediate central limb, only said second outer limb having a zone of reduced crosssection so that said first outer limb has a greater force of attraction than said second outer limb when said core is energized; a pin arranged on said frame near said second outer limb; a substantially planar pallet pivotally mounted on said frame for rocking motion about said pin; resilient means operatively connected to said pallet to urge the same into an end position farthest away from said core; a laminated armature cooperating with said magnetic core and having a pair of opposite sides and a pair of opposite ends; and holding means on said pallet cooperating with said armature to hold the same with play allowing a limited displacement of said armature with respect to said pallet in all directions, said holding means comprising four projections fixed to said pallet, being substantially normal thereto, extending toward said core, and respectively facing said sides and ends of said armature so as to limit the play of the same in all directions in a plane parallel to said planar armature, one of said four projections being located at a greater distance from said pin than said first limb of said core and having fixedly connected thereto a member extending toward said pin and being substantially parallel to said plane so as to limit the movement of said armature in a direction normal to said plane.

3. An electromagnetic actuator for contactcrs and circuit breakers, comprising in combination, a frame; an E-shaped magnetic core arranged on said frame and having a first and a, second outer and an intermediate central limb, only said second cuter limb having a zone-of reduced crosssection so that said first outer limb has a greater force of attraction than saidsecond outer limb when said core is energized; a pin arranged on said frame near said second outer limb; a substantially planar pallet pivotally mounted on said frame for rocking motion about said pin; resilient means operatively connected to said pallet to urge the same into an end position farthest away from said core; a laminated armature cooperating with said magnetic core and having a pair of opposite sides and a pair of opposite ends; and holding means on said pallet cooperating with said armature to hold the same with play allowing a limited displacement of said armature with respect to said pallet in all directions, said holding means comprising four projections fixed to said pallet, being substantially normal thereto, extending toward said core, and respectively facing said sides and ends of said armature so as to limit the play of the same in all directions in a plane parallel to said planar armature, one of said four projections being located at a greater distance from said pin than said first limb of said core and having fixedly connected thereto a member extending toward said pin and being substantially parallel to said plane so as to limit the movement of said armature in a direction normal to said plane, the projection opposite said one projection being formed with a shoulder providing a face parallel to said plane so as to also limit movement of said armature in a direction normal to said plane.

ANDRE BLANCHET.

REFERENCES CITED The following references are of record in the file of this patent:

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